Modern portable electronic devices are demanding increasing amounts of electrical power and chemical batteries are often the performance bottleneck for such devices. Wireless products, such as personal digital assistants, mobile phones, entertainment devices, and next generation laptops in particular have a great demand for sustained power. For long-term portable operations, fuel cells are an attractive solution. Fuel cells, like batteries, efficiently convert chemical energy into electricity, but have additional advantages, such as higher energy density and the capability for instant refueling. Fuel cells are typically fuelled by hydrogen gas, but there are technological challenges in storing and delivering hydrogen gas to the fuel cells in a cost effective and efficient manner. One particular challenge is to provide a fuel supply that is inexpensive, safe, light and compact enough to be readily portable yet store enough hydrogen to provide a useful amount of fuel to the fuel cell. State of the art means for storing hydrogen include metal hydride canisters to store hydrogen at relatively low pressures, and pressure tanks to store compressed hydrogen at elevated pressures. Both approaches have drawbacks; for example, metal hydride storage is relatively safe but has a low energy density to weight ratio, and compressed hydrogen may have a high energy density to weight ratio but requires high strength and expensive containment solutions.
Other efforts have been directed at generating hydrogen gas from a hydrogen-containing fuel precursor such as sodium borohydride. In such approaches, the fuel solution is exposed to a reactant to facilitate the production of hydrogen gas. This reactant is typically a liquid reactant that must be pumped to a reaction site. In conventional systems, the pump is either be placed within the fuel generator or within the fuel cell system. Placement of the pump within fuel generator allows for a simple fluid interface, requiring only a fuel outlet, but also increases the cost of the fuel generator, which is typically a disposable component and thus, cost sensitive. Placement of the pump within the fuel cell system decreases the cost of the fuel generator, but adds the technical complexities of managing multiple fluid ports, as the liquid reactant must be pumped into the fuel cell system and back into the fuel generator.
Therefore, there exists a need for a better pump assembly in the fuel cell system to pump liquid reactant to the reaction site. More specifically, there exists a need for a pump assembly that splits the pump actuator from the fluid-contacting components, effectively decreasing the cost of fuel generator while minimizing the technical complexities of the system arising from multiple fluid ports.